A recent study conducted by researchers at the California Department of Public Health and the CDC has found that most countries have not reported cases of infant botulism.
“This limited reporting of the disease to date contrasts with the known global occurrence of Clostridium botulinum spores in soils and dust and suggests that infant botulism may be underrecognized, underreported or both. When bulbar palsies, hypotonia, and weakness are present, physicians should consider the possibility of infant botulism even if the patient has not been fed honey,” according to the investigators. The study was recently published in Pediatrics.
Infant botulism was first recognized in 1976 in the United States. The purpose of this study was to review the worldwide occurrence of reported infant botulism between 1976 and 2006.
The researchers used active and passive surveillance to collect information on infant botulism cases. A case was defined as laboratory-confirmed botulism in an infant 12 months of age or younger that was not caused by ingesting botulinum toxin in food.
Cases in the United States
Three methods were used to gather information on infant botulism cases in the United States. These included surveillance through provision of Botulism Immune Globulin Human Intravenous (BIG-IV) for suspected infant botulism cases across the country, surveillance in California, and collaboration with the CDC.
The researchers identified 1,070 cases of infant botulism that occurred in the United States between 1976 and 1991. Approximately half (511 cases) of these infants were diagnosed by the Infant Botulism Treatment and Prevention Program (IBTPP), and 559 cases were reported to the CDC through passive surveillance.
In 1992, a clinical trial of BIG-IV began in California. Between 1992 and 2006, 789 infants with botulism were given BIG-IV by the IBTPP. Additionally, during this same time period, 560 infants with botulism were identified but did not receive BIG-IV. Eighty-seven of these cases were confirmed by the IBTPP laboratory, while most, 473 cases, were identified through passive surveillance to the CDC.
This translates to 2,419 cases identified in the United States between 1976 and 2006, which is an average of 2.1 cases per 100,000 live births. Mean age at onset of infant botulism was 13.8 weeks, with a range of 0 to 52 weeks.
Of the 2,419 cases, nine (0.4%) were identified in outpatient settings and never required hospitalization for their illness. Twenty (0.8%) patients died after hospital admission for infant botulism; two (10%) of these patients had received BIG-IV.
A photomicrograph of Clostridium botulinum type A viewed using a Gram stain technique.
Of the infants diagnosed in California, the percentage who had a history of honey exposure decreased significantly during the 30-year study period (39.7% in the 1970s to 14.7% in the 2000s).
In other countries, active and passive surveillance was used to identify cases reported in the literature, as well as unreported cases. The cases not reported in the literature included 17 infants in Canada, 15 infants in Australia, five infants in Japan, four infants in Italy, and two infants in Sweden.
Three methods were used to identify cases in countries other than the United States: PubMed searches, University of California-Berkeley School of Public Health library searches, and IBTPP file searches. These three methods found 524 infant botulism cases in 25 countries in Asia, Europe, Australia, North America, and South America. Countries with the highest numbers of cases were Argentina (366), Australia (32), Canada (27), Italy (26) and Japan (22).
The first case of infant botulism was recognized in the United States in late 1976. Approximately a year later, England and Australia reported their first cases. During the next 30 years, recognition of infant botulism cases has spread globally.
Of the cases reported outside the United States, demographic and clinical information were available for approximately 20% of cases. As in the cases in the United States, infant botulism was reported in girls and boys in almost equal numbers. At disease onset, patients’ average age was 14.3 weeks, and their average inpatient hospital stay lasted 7.3 weeks. During hospitalization, 68% of infants with available information required intubation or ventilation. Fifty-nine percent of cases with available information had a history of honey exposure. Most infants (83.4%) had illness caused by type A toxin, while 10.7% had illness caused by type B toxin; and 0.9% had illness caused by C. butyricum type E toxin. Only six infants with botulism died after hospital admission.
Infants with botulism who were hospitalized both inside and outside the United States had similar age and gender distributions.
“The age distribution of infant botulism, centering around 3 to 4 months of age and spanning from the first weeks of life to approximately 1 year of age, continues to be a defining feature of the disease. Perhaps coincidentally, the age distribution of hospitalized patients with infant botulism is essentially indistinguishable from the age distribution of victims of sudden infant death syndrome cases. In addition to the United States, five countries have documented the presence of C. botulinum in the intestinal contents of infants who died suddenly. These findings are consistent with the possibility that C. botulinum may cause a portion of the deaths now classified as SIDS in some, but not all, parts of the world,” the researchers wrote.
From these study results, researchers have concluded that the occurrence of infant botulism that is not related to the ingestion of honey may reflect the environmental distribution of the spores and the inability of physicians to identify and report the disease. “More accurate case ascertainment worldwide would be possible by mandating the reporting of infant botulism to each country’s national health agency,” the researchers wrote. – by Michelle Stephenson
For more information:
- Koepke R, Sobel J, Arnon SS. Global occurrence of infant botulism, 1976-2006. Pediatrics. 2008;122:e73-e82.